Synthesis and structural analysis of cis-bis(1,10-phenanthroline)dicarbonyl ruthenium(II) 1.72-trifluoromethanesulfonate 0.28-hexafluoridophosphate

Ruthenium(II) complexes containing both 1,10-phenanthroline (Phen) and carbonyl (CO) ligands are important molecules for various applications including catalysis. In this work, the molecular structure of [Ru(Phen)2(CO)2]2+ was determined via X-ray diffraction analysis for the first time. The complex exhibits substitutional disorder of one of counter-anions in the asymmetric unit, with different occupancies for CF3SO3- (0.72) and PF6- (0.28). The ruthenium atom is coordinated in a distorted octahedral environment by two carbonyl carbon atoms and four nitrogen atoms from bis-Phen ligands. The cation displays a cis configuration of the carbonyl ligands. Several hydrogen bonds and π-π interactions are present in the crystal. In addition to structural characterization, IR spectral data for the complex is compared with calculated values. These results provide fundamental data for understanding various properties of related ruthenium complexes.

N-Heterocyclic Carbene Mediated Organocatalysis Reactions

Arduengo et al., isolated the first ‘bottleable’ carbene, the first N-heterocyclic carbene (NHC) 1,3-di(adamantyl)imidazol-2-ylidene resulted to an explosion of experimental and theoretical studies of novel NHCs being synthesized and analyzed have huge practical significance. These compounds emerged as successful ligands for coordinating transition metals, the complexes with NHC show diverse applications in the field of catalysis and organic transformation, NHC as ligand to main group elements and their properties and applications. Here this chapter provides the concise overview of N-heterocycle carbene as an organocatalyst that provides different organic transformation on to a carbonyl group. The majority of the NHC catalyzed reactions are employed in the phenomenon of reversing the electrophilic character of carbonyl carbon to nucleophilic carbon (umpolung activity) on coordination suggests benzoin, Stetter and hydroacylation reactions. Also, non-umpolung activity of bis-electrophile α,β-unsaturated acylazoliums reaction with suitable bis-nucleophiles in the organic synthesis have been studied.

Dimethyl 4,5-dichlorophthalate

While endeavoring to synthesize new chlorinated ligands for ruthenium-based metathesis catalysts, the title compound dimethyl 4,5-dichlorophthalate, C10H8Cl2O4, was prepared from commercially available 4,5-dichlorophthalic acid in ∼77% yield. The title molecule, which also finds utility as a precursor molecule for the synthesis of drugs used in the treatment of Alzheimer's disease, shows one carbonyl-containing methyl ester moiety lying nearly co-planar with the chlorine-derivatized aromatic ring while the second methyl ester shows a significant deviation of 101.05 (12)° from the least-squares plane of the aromatic ring. Within the crystal, structural integrity is maintained by the concerted effects of electrostatic interactions involving the electron-deficient carbonyl carbon atom and the electron-rich aromatic ring along the a-axis direction and C—H...O hydrogen bonds between neighboring molecules parallel to b.

Regioselective Reduction of 1H-1,2,3-Triazole Diesters

Regioselective reactions can play pivotal roles in synthetic organic chemistry. The reduction of several 1-substituted 1,2,3-triazole 4,5-diesters by sodium borohydride has been found to be regioselective, with the C(5) ester groups being more reactive towards reduction than the C(4) ester groups. The amount of sodium borohydride and reaction time required for reduction varied greatly depending on the N(1)-substituent. The presence of a β-hydroxyl group on the N(1)-substituent was seen to have a rate enhancing effect on the reduction of the C(5) ester group. The regioselective reduction was attributed to the lower electron densities of the C(5) and the C(5) ester carbonyl carbon of the 1,2,3-triazole, which were further lowered in cases involving intramolecular hydrogen bonding.

Hydroxyl-containing bis(sulfonates). Reaction of 1,4-dibromo-2,3-butanedione with water, methanol and sodium sulfite

Sulfonates are well-known substances with a variety of applications, e.g. as surfactants. On the other hand, bis(sulfonates) bearing hydroxyl or keto group(s) in between the sulfonate groups can be used with or without further modification as starting materials for the preparation of new type of molecules capable to form either complexes or in general supramolecular structures. The synthesis of three hydroxyl-bearing bis(sulfonates), 2-hydroxypropane-1,3-bis(sodium sulfonate) 4, DL-2,3-dihydroxybutane-1,4-bis(sodium sulfonate) 8, and sodium 2,3,4-trihydroxy-1-sulfonate 7 (as by-product) via the Strecker sulfonation are described. Interestingly, under similar conditions, sulfonation of 1,4-dibromo-2,3-butanedione 9 was found to be very complicated and no pure product could be isolated, despite previously reported results on sulfonation of α-halogenated ketones in high yields. There are indications that SO3 2 - attacks at the carbonyl carbon of 9 followed by rearrangement and expulsion of SO4 2 - . 1,4-dibromo-2,3-butanedione 9, bearing two keto groups next to methylene groups, can potentially exist as enols or in the case of its solution in hydroxylic solvents in the form of hemiketals or geminal diols. This behavior of 9 when is dissolved in CDCl3, CD3OD and D2O was studied by means of UV-Vis, 1H and 13C NMR and the nature of the adducts formed was elucidated.

Rubesanolides F and G: Two Novel Lactone-Type Norditerpenoids from Isodon rubescens

A phytochemical investigation of the leaves of the medicinal plant Isodon rubescens led to the isolation of the two new degraded abietane lactone diterpenoids rubesanolides F (1) and G (2). Their structures were elucidated based on the analyses of the HRESIMS and 1D/2D NMR spectral data, and their absolute configurations were determined by ECD spectrum calculations and X-ray single crystal diffraction methods. Compounds 1 and 2, with a unique γ-lactone subgroup between C-8 and C-20, were found to form a carbonyl carbon at C-13 by removal of the isopropyl group in an abietane diterpene skeleton. Rubesanolide G (2) is a rare case of abietane that possesses a cis-fused configuration between rings B and C. The two isolates were evaluated for their biological activities against two cancer cell lines (A549 and HL60), three fungal strains (Candida alba, Aspergillus niger and Rhizopus nigricans) and three bacterial strains (Escherichia coli, Staphylococcus aureus and Bacillus subtilis).

Molecular structure of fac-[Mo(CO)3(DMSO)3]

The title compound, tricarbonyltris(dimethyl sulfoxide)molybdenum, [Mo(C2H6OS)3(CO)3] or fac-[Mo(CO)3(DMSO)3], crystallizes in the triclinic space group P\overline{1} with two molecules in the unit cell. The geometry around the central molybdenum is slightly distorted octahedral and the facial isomer is found exclusively. The packing within the crystal is stabilized by three-dimensional non-classical intermolecular hydrogen-bonding contacts between individual methyl substituents of dimethyl sulfoxide and the oxygen atoms of either another dimethyl sulfoxide or a carbonyl ligand on adjacent complex molecules. The observed bond lengths in the carbonyl ligands and between carbonyl carbon atoms and molybdenum are correlated to the observed FT–IR bands for the carbonyl stretches and compared to respective metrical parameters of related complexes.

Synthesis and Reactivity of Uhle’s Ketone and its Derivatives

The Uhle’s ketone and its derivatives are highly versatile intermediates for the synthesis of a variety of 3,4-fused tricyclic indole frameworks, i.e. indole alkaloids of the ergot family, that are found in various bioactive natural products and pharmaceuticals. Therefore, the development of a convenient preparative method for this structural motif as well as its opportune/useful derivatization have been the subject of longstanding interest in the fields of synthetic organic chemistry and medicinal chemistry. Herein, we summarize recent and less recent methods for the preparation of Uhle’s ketone and its derivatives as well as its main reactivity towards the synthesis of bioactive substances. Regarding the preparation, it can be roughly classified into two categories: a) using 4-unfunctionalized and 4-functionalized indole derivatives as starting materials to construct a fused six-member ring, and b) constructing the indole ring through intramolecular cycloaddition. Principally, the reactivity of the cyclic Uhle’s ketone shown here is derived from the classical electrophilicity of the carbonyl carbon or the acidity of the α-hydrogen and, though less intensively investigated, chemical reactions that induce ring expansion to form novel ring skeletons.

Preparation of Microwave Multi-Adsorbent Nanocomposites Based on Copper, Iron Carbonyl, Carbon Nanofiber, Graphite Nanoflake and Polypyrrole

The composites of Cu, Carbonyl iron (CI), carbon nanofiber (CNF), graphite nanoflake (GNF)/polypyrrole (PPy) and [(Cu-CI-CNF-GNF) 0.5-PAA]-PPy0.5 were synthesized via different methods by in-situ polymerization on the surface of nanoparticles (NPs) with core-shell structure. This paper describes a method for polyacrylic acid (PAA) coating of NPs in aqueous solution. Then PPy coating was performed by template polymerization on NPs-PAA. Morphology, magnetic and conductivity properties were observed via scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and four probe method, respectively. The microwave characterization of nanocomposite was evaluated through arch test based on a network analyzer. The PPy nanocomposites possessed the excellent microwave multi absorbers properties in 2-18 GHz. It was also found that nanocomposites with 50% w/w and light weight exhibit good microwave absorbing properties in 2-3 GHz and 5-14 GHz frequency, so can be used to cellphone, radio frequency and radar shielding.

High glycine content in TDP-43: a potential culprit in limbic-predominant age-related TDP-43 encephalopathy

Numerous risk factors for heart disease or dementia harbor over 10% valine plus glycine content. Interestingly, TDP-43 contains 6.0% valine and 13.3% glycine, and the buildup of this protein in the brains of patients with limbic-predominant age-related TDP-43 encephalopathy has dire consequences. The two γ-methyl groups in valine enable hyperconjugation, which enhances the van der Waals interaction between its side group and the carbonyl carbon. This extends the C=O bond length, and this weakened C=O bond augments the secondary chemical bonding of the carbonyl oxygen atom to cations. This, in turn, promotes the formation and buildup of insoluble and rigid salts such as calcium oxalate, which is postulated to be a major cause of heart disease. Similarly, the long C=O bond length in glycine results in a weakened C=O bond with an enhanced affinity toward cations and the formation of insoluble salts. Further, several prion proteins possess a high glycine content of approximately 20%. The insoluble calcium salts produced may promote aggregate formation via secondary chemical bonding between calcium and glycine, as well as between calcium and valine. Chemical and biochemical insights will help us to better understand the etiology of disorders linked to protein aggregates.